Browsing by Author "Chan, YJ"

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Au/Ge/Pd ohmic contacts to n-GaAs with the Mo/Ti diffusion barrier
(1996-12-01)
Chai, CY
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Huang, JA
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Lai, YL
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Wu, JW
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Chang, CY
The influences of the As-outdiffusion and Au-indiffusion on the performances of the Au/Ge/Pd/n-GaAs ohmic metallization systems are clarified by investigating three different types of barrier metal structures Au/Ge/Pd/GaAs, Au/Ti/Ge/Pd/GaAs, and Au/Mo/Ti/Ge/Pd/GaAs. The results indicate? that As-outdiffusion leads to higher specific contact resistivity, whereas Au-indiffusion contributes to the turnaround of the contact resistivity at even higher annealing temperature. For Au/Mo/Ti/Ge/Pd/n-GaAs samples, they exhibit the smoothest surface and the lowest specific contact resistivity with the wildest available annealing temperature,range, Moreover, Auger electron spectroscopy depth profiles show that the existing Ti oxide for the Mo/Ti bilayer can very effectively retard Au-indiffusion, reflecting the onset of the turnaround point at much higher annealing temperature.
Excellent Au/Ge/Pd ohmic contacts to n-type GaAs using Mo/Ti as the diffusion barrier
(1996-04-01)
Chai, CY
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Huang, JA
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Lai, YL
;
Wu, JW
;
Chang, CY
Au/Ge/Pd metallization system using Mo/Ti as the diffusion barrier between the Au overlayer and the Ge/Pd underlayer has been performed for the first time to achieve excellent ohmic contacts to n(+)-GaAs with the Si-doping concentration of about 2 x 10(18) cm(-3). The minimum specific contact resistivity as low as 1.2 x 10(-7) Ohm . cm(2) can be obtained after the rapid thermal annealing at 325 degrees C for 60 s, which is much lower than those of the conventional Au/Ge/Pd metallization systems. Furthermore, the available annealing temperature range for such low specific contact resistivities is also significantly extended from 325 degrees C to 400 degrees C. The improvement is attributed to the effective retardation of As-outdiffusion by the Mo/Ti barrier.
High-performance An/Ti/Ge/Pd ohmic contacts on n-Type In0.5Ga0.5P
(1996-04-01)
Chai, CY
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Wu, JW
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Guo, JD
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Huang, JA
;
Lai, YL
High-performance Au/Ti/Ge/Pd ohmic contacts on n(+)-In0.5Ga0.5P have been fabricated for the first time. Using an n(+)-In0.5Ga0.5P epitaxial layer grown by low pressure metalorganic chemical vapor deposition (LP-MOCVD) with a Si dopant concentration of about 2 x 10(18) cm(-3), the minimum specific contact resistivity is as low as 1.2 x 10(-5) Ohm . cm(2), which is much lower than that of AuGeNi contacts after rapid thermal annealing at 400 degrees C for 60 s. The thermal stability of the Au/Ti/Ge/Pd system is significantly higher than that of conventional AuGeNi due to the introduction of the Ti barrier layer. Many holes and islands are observed on the surfaces of samples annealed at high temperature. The outdiffusion of P from the decomposed In0.5Ga0.5P substrate and agglomeration of Pd and Ge are the primary causes of contact degradation.
Molecular beam epitaxy regrowth and device performance of GaAs-based pseudomorphic high electron mobility transistors using a thin indium passivation layer
(2000-08-01)
Chen, SS
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Lin, CC
;
Peng, CK
;
Chan, YJ
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材料科學與工程學系
Using the technique of molecular beam epitaxy, an indium passivation layer as thin as several tens of Angstrom was implemented to protect underlying III-V epilayers from carbon and oxygen contamination. After the subsequent desorption of the passivation layer, GaAs-based pseudomorphic high electron mobility transistors (PHEMTs) were regrown. Negligible residual carriers were detected at the interface between the regrown PHEMTs and the underlying layer, resulting in a superior performance. The regrown PHEMTs with a 1 x 100 mum(2) gate demonstrated an extrinsic transconductance g(me) as high as 330 mS mm(-) (1). Microwave measurements showed that the current gain cut-off frequency f(t) was 26.5 GHz and the maximum oscillation frequency f(max) was up to 48 GHz. A small-signal equivalent circuit model of the regrown PHEMTs was also evaluated. (C) 2000 Kluwer Academic Publishers.